Mechanism of the heavy-ion charge exchange reaction 12C(12C, 12N)12B at 35 MeV/nucleon

摘要

The heavy-ion charge exchange reaction 12C(12C,12N)12B has been studied at E(12C)=35 MeV/nucleon. Angular distributions in the range 3.7-12.1° (c.m.) have been measured for the 1+ (0.0 MeV), 2+ (0.95 MeV), 2- (1.67 MeV), and 4-,2- (4.5 MeV) states in 12B. A broad peak at 7.8 MeV excitation was also observed. Microscopic one-step distorted-wave Born approximation calculations yield Vστ strengths ≥2 times those obtained in (p,n) reactions at similar energies per nucleon. Although this is significantly smaller than Vστ values obtained in other heavy-ion charge exchange studies, mostly carried out at energies less than 10 MeV/nucleon, it is concluded that the reaction mechanism is still dominated by sequential transfer (two-step) processes at 35 MeV/nucleon. A rough estimate indicates that one-step processes will dominate at bombarding energies above about 50 MeV/nucleon.